MAX1243BCSA Maxim Integrated Products, MAX1243BCSA Datasheet - Page 23

• Manufacturer Part Number: MAX1243BCSA
• Description: ADC (A/D Converters) Integrated Circuits (ICs)
• Manufacturer: Maxim Integrated Products

Specifications of MAX1243BCSA

• Number Of Adc Inputs: 1
• Architecture: SAR
• Conversion Rate: 73 KSPs
• Resolution: 10 bit
• Input Type: Voltage
• Interface Type: 3-Wire (SPI, QSPI, Microwire)
• Voltage Reference: External
• Supply Voltage (max): 5.25 V
• Supply Voltage (min): 2.7 V
• Maximum Power Dissipation: 471 mW
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Package / Case: SO-8
• Minimum Operating Temperature: 0 C
• Lead Free Status / Rohs Status: No

The MAX1221/MAX1223/MAX1343 can operate from an
internal oscillator. The internal oscillator is active in
clock modes 00, 01, and 10. Figures 6, 7, and 8 show
how to start an ADC conversion in the three internally
timed conversion modes.
Read out the data at clock speeds up to 25MHz
through the SPI interface.
Set CKSEL1 and CKSEL0 in the setup register to 11 to
set up the interface for external clock mode 11. See
Table 5. Pulse SCLK at speeds from 0.1MHz to
3.6MHz. Write to SCLK with a 40% to 60% duty cycle.
The SCLK frequency controls the conversion timing.
See Figure 9 for clock mode 11 timing. See the ADC
Conversions in Clock Mode 11 section.
Address the reference through the setup register, bits 3
and 2. See Table 5. Following a wake-up delay, set
REFSEL[1:0] = 00 to program both the ADC and DAC
for internal reference use. Set REFSEL[1:0] = 10 to pro-
gram the ADC for internal reference use without a
wake-up delay. Set REFSEL[1:0] = 10 to program the
DAC for external reference, REF1. When using REF1 or
REF2/AIN_ in external-reference mode, connect a 0.1µF
capacitor to AGND. Set REFSEL[1:0] = 01 to program
the ADC and DAC for external-reference mode. The
DAC uses REF1 as its external reference, while the
ADC uses REF2 as its external reference. Set
REFSEL[1:0] = 11 to program the ADC for external dif-
ferential reference mode. REF1 is the positive reference
and REF2 is the negative reference in the ADC external
differential mode.
When REFSEL[1:0] = 00 or 10, REF2/AIN_ functions as
an analog input channel. When REFSEL[1:0] = 01 or 11,
REF2/AIN_ functions as the device’s negative reference.
Issue a command byte setting bit 0 of the conversion
register to one to take a temperature measurement.
Table 3. GPIO Maximum Sink/Source
Current
CURRENT
Source
Sink
12-Bit, Multichannel ADCs/DACs with FIFO,
______________________________________________________________________________________
Temperature Measurements
GPIOA0, GPIOA1
Temperature Sensing, and GPIO Ports
(mA)
15
15
ADC/DAC References
MAX1221/MAX1343
Clock Modes
GPIOC0, GPIOC1
External Clock
Internal Clock
(mA)
4
2
See Table 4. The MAX1221/MAX1223/MAX1343 perform
temperature measurements with an internal diode-con-
nected transistor. The diode bias current changes from
68µA to 4µA to produce a temperature-dependent bias
voltage difference. The second conversion result at 4µA
is subtracted from the first at 68µA to calculate a digital
value that is proportional to absolute temperature. The
output data appearing at DOUT is the digital code
above, minus an offset to adjust from Kelvin to Celsius.
The reference voltage used for the temperature mea-
surements is always derived from the internal reference
source to ensure that 1 LSB corresponds to 1/8 of a
degree Celsius. On every scan where a temperature
measurement is requested, the temperature conversion
is carried out first. The first 2 bytes of data read from
the FIFO contain the result of the temperature measure-
ment. If another temperature measurement is per-
formed before the first temperature result is read out,
the old measurement is overwritten by the new result.
Temperature results are in degrees Celsius (two’s com-
plement). See the Applications Information section for
information on how to perform temperature measure-
ments in each clock mode.
The MAX1221/MAX1223/MAX1343 communicate
between the internal registers and the external circuitry
through the SPI-compatible serial interface. Table 1
details the command byte, the registers, and the bit
names. Tables 4–12 show the various functions within
the conversion register, setup register, unipolar-mode
register, bipolar-mode register, ADC averaging regis-
ter, DAC select register, reset register, and GPIO com-
mand register, respectively.
Select active analog input channels, scan modes, and
a single temperature measurement per scan by issuing
a command byte to the conversion register. Table 4
details channel selection, the four scan modes, and
how to request a temperature measurement. Start a
scan by writing to the conversion register when in clock
mode 10 or 11, or by applying a low pulse to the
CNVST pin when in clock mode 00 or 01. See Figures 6
and 7 for timing specifications for starting a scan with
CNVST.
A conversion is not performed if it is requested on a
channel or one of the channel pairs that has been con-
figured as CNVST or REF2. For channels configured as
differential pairs, the CHSEL0 bit is ignored and the two
pins are treated as a single differential channel. For the
MAX1221/MAX1343, the CHSEL3 bit must be zero.
Register Descriptions
Conversion Register
23